<template>
  <el-tooltip effect="dark" content="theme" placement="bottom">
    <el-color-picker
        v-model="theme"
        class="theme-picker"
        size="small"
        popper-class="theme-picker-dropdown"></el-color-picker>
    </el-tooltip>
</template>

<script>
// const version = require('element-ui/package.json').version // element-ui version from node_modules
const ORIGINAL_THEME = '#409EFF' // default color
import { mapMutations } from 'vuex';
export default {
  data() {
    return {
      chalk: '', // content of theme-chalk css
      theme: ORIGINAL_THEME
    }
  },
  created() {
    this.theme = this.$store.state.layout.setting.theme.color || ORIGINAL_THEME ;
  },
  watch: {
    theme: {
       handler(val, oldVal){
           if (typeof val !== 'string') return
            const themeCluster = this.getThemeCluster(val.replace('#', ''))
            const originalCluster = this.getThemeCluster(oldVal.replace('#', ''))
            console.log(themeCluster, originalCluster)
            const getHandler = (variable, id) => {
                return () => {
                const originalCluster = this.getThemeCluster(ORIGINAL_THEME.replace('#', ''))
                const newStyle = this.updateStyle(this[variable], originalCluster, themeCluster)

                let styleTag = document.getElementById(id)
                if (!styleTag) {
                    styleTag = document.createElement('style')
                    styleTag.setAttribute('id', id)
                    document.head.appendChild(styleTag)
                }
                styleTag.innerText = newStyle
                }
            }

            const chalkHandler = getHandler('chalk', 'chalk-style')

            if (!this.chalk) {
                const url = `https://unpkg.com/element-plus/lib/theme-chalk/index.css`
                this.getCSSString(url, chalkHandler, 'chalk')
            } else {
                chalkHandler()
            }

            const styles = [].slice.call(document.querySelectorAll('style'))
                .filter(style => {
                const text = style.innerText
                return new RegExp(oldVal, 'i').test(text) && !/Chalk Variables/.test(text)
                })
            styles.forEach(style => {
                const { innerText } = style
                if (typeof innerText !== 'string') return
                style.innerText = this.updateStyle(innerText, originalCluster, themeCluster)
            })
            this.SET_THEMECOLOR(this.theme);
            // this.$message({
            //     message: '换肤成功',
            //     type: 'success'
            // })
            },
            immediate:false

       }, 
      
  },

  methods: {
    ...mapMutations('layout', ['SET_THEMECOLOR']),
    updateStyle(style, oldCluster, newCluster) {
      let newStyle = style
      oldCluster.forEach((color, index) => {
        newStyle = newStyle.replace(new RegExp(color, 'ig'), newCluster[index])
      })
      return newStyle
    },

    getCSSString(url, callback, variable) {
      const xhr = new XMLHttpRequest()
      xhr.onreadystatechange = () => {
        if (xhr.readyState === 4 && xhr.status === 200) {
          this[variable] = xhr.responseText.replace(/@font-face{[^}]+}/, '')
          callback()
        }
      }
      xhr.open('GET', url)
      xhr.send()
    },

    getThemeCluster(theme) {
      const tintColor = (color, tint) => {
        let red = parseInt(color.slice(0, 2), 16)
        let green = parseInt(color.slice(2, 4), 16)
        let blue = parseInt(color.slice(4, 6), 16)

        if (tint === 0) { // when primary color is in its rgb space
          return [red, green, blue].join(',')
        } else {
          red += Math.round(tint * (255 - red))
          green += Math.round(tint * (255 - green))
          blue += Math.round(tint * (255 - blue))

          red = red.toString(16)
          green = green.toString(16)
          blue = blue.toString(16)

          return `#${red}${green}${blue}`
        }
      }

      const shadeColor = (color, shade) => {
        let red = parseInt(color.slice(0, 2), 16)
        let green = parseInt(color.slice(2, 4), 16)
        let blue = parseInt(color.slice(4, 6), 16)

        red = Math.round((1 - shade) * red)
        green = Math.round((1 - shade) * green)
        blue = Math.round((1 - shade) * blue)

        red = red.toString(16)
        green = green.toString(16)
        blue = blue.toString(16)

        return `#${red}${green}${blue}`
      }

      const clusters = [theme]
      for (let i = 0; i <= 9; i++) {
        clusters.push(tintColor(theme, Number((i / 10).toFixed(2))))
      }
      clusters.push(shadeColor(theme, 0.1))
      return clusters
    }
  }
}
</script>